Problem: The arithmetic sequence $(a_i)$ is defined by the formula: $a_i = 5 - 5(i - 1)$ What is $a_{11}$, the eleventh term in the sequence?
Explanation: From the given formula, we can see that the first term of the sequence is $5$ and the common difference is $-5$ To find $a_{11}$ , we can simply substitute $i = 11$ into the given formula. Therefore, the eleventh term is equal to $a_{11} = 5 - 5 (11 - 1) = -45$.